Primary dry cell



W. R. KEMPF PRIMARY DRY CELL May 17, 1960 Filed Jan. 22, 1957 I N VEN TOR.

UnitedStates Patent O l2,937,222 PRIMARY DRY CELL Application January '22, 1957, Serial No. 635,256

1 claim. (cl. 13s-115) This invention relates to a primary dry'cell and more particularly relates to disk type primary dry cells and to a method of manufacturingv the same. f

In assignees copending application Serial No. 548,660, filed November 23, 1955, now Patent No. 2,837,593 there is disclosed a disk typeprimary dry cell housed within a casingwhich consists of upper and lower shells with the periphery of the upper shell being curled about a bead at the edge of the lower shell Ito fasten and. seal the two together. This curling operation is performed in assembly dies which contain a curling ring for curling the periphery of the upper shell about the bead on the lower shell. In the perfomance of this curlingy operation by dies of this type it has been found that a certain metal iiow occurs and that this tends to deform the center portion of the upper shell and deleteriously affect the electrical connection between the upper shell and the anode which is contained therein.

According to the present invention it has now been found that this diIicult-y may be eliminated and a good connection between the anode and upper shell maintained, if the center portion of the upper shell is spherically domed upwards. vided in a form to receive such a domed upper shell, the tendency to metaljow is diverted into another portion of the upper shell in a manner such that the electrical connection between the anode and shell is not affected. In addition, a domed anode is compressed into the domed .portion of the upper shell and this anode shape results in better physical strength of the anode as it is consumed during cell drainage.

It is accordingly a primary object of the present invention to provide an improved primary cell Vformed of upper and lower shells and having a domed upper shell.

It is another object of the invention to provide animproved method of manufacturing disk type primary cells.

It is another object of the invention to provide an improveddisk type primary cell comprised of a pair of shells wherein one shell is domed and contains a domed electrode in electrical contact therewith.

It is another object of the invention to provide an improved disk type primary cell having a domed shell portion in which a domed electrode is iitted to provide for good contact between the electrode and shell and tov insure high physical strength of the electrode as it is consumed during drainage of the cell.

These and further objects and advantages of the invention will become apparent upon reference to the following specication and claims and appended drawings wherein:

Figure l is a vertical section showing the manufacture of a disk -type primary cell according to the method heretofore used; and

When the assembly die is pro'-v mentioned copending application, a disk type primary dry 12.V The lower shellv10 has vertical peripheral walls 14 which are flared outwardly at 16 and provided with a peripheral bead 18. A suitable insulating gasket 20 is mounted over the upper face of the bead 18. The upper shell 12 has an annular groove 22 concen trically located and has a depending skirt 24 which over-Y lies the gasket 20. A suitable anode 26, which may consist of zinc powder compacted into the depression formed by groove '22 on the undersideof the upper shell, en gages the undersurface of the upper shell. 1.

This cell is assembled in an `assembly die consisting vof an upper'die member 28 and a composite lower die' shown generally at 30. The upper die member 28 is provided with a recess having a at bottom 32 and a v edge and having a central bore 42. A support plunger 44is resiliently mounted in the bore 42 and supports the lower shell 10. e l V In the manufacture of cells by means of this assembly a cell is mounted as shown in Figure l and the upper die V28 moves downwardly. As the die 28 moves below the position shown in Figure l, the skirt 24 on upper shell 12 commences to curl in curling ring 4i) and is curled about bead 18 on the lower shell 10. The support plunger 44 permits theA base of lower shell 10 to slide down within the bore 42 in die 30 so that no pressure is applied to this portion of the cell.

During the curling operation the upper shell resists forming and pressure is transmitted back from the bottom edge of the skirt 24 to the center of the upper shell 12. Since the shell is backed up by .the punch, it cannot flex upward, but it can ex downward. Downward flexing occurs to create the space shown at 46. This downward ilexing cracks the anode pellet and tends to break the bond between the pellet and the upper shell 12. When this bond is broken there is a considerable danger that a poor electrical contact between the case top and the pellet will develop thereby producing a defective cell.

Referring to Figure 2, which shows a cell assembly according to the invention, there is seen a disk type cell comprising a lower shell 48 and upper shell 50. yThe lower shell 48 is provided with an upstanding peripheral wall 52 having an outwardly ared wall portion 54, as described in further detail in assignees aforementioned copending application. A bead 56 is provided at the upper edge of outwardly liared portion 54. In assembly, this lower shell 48 is carried ona resiliently mounted plunger 58 within a lower die cylinder 60 having a curling ring 62. The upper shell 50 is provided with an annular concentric groove 64, ring portion 66 and depending skirt 68. A gasket 70 is mounted over the bead 56 on lower shell 48, as described in the aforementioned copending application.

According to the invention vthe lupper' shell 50 is provided with a sperical domed central portion 72' and this is received within a mating domed recess 74 in an upper die 76. This die is provided with a suitable ridge 78 for mating with groove 64 and with a suitable annular depression 80 for receiving the ring 66. An anode 82, which mayV consist of powdered zinc, is compressed into the depression formed in the underside of the upper shell 3 ward flexture of the center of the shell is completely eliminated. Because of the strength of the dome, and further because there is no. tendency to deect downward, the center 72 of upper shell 50 does not leave the surface 74 of upper die 76 and does not interfere with the electrical contact between the anode and upper shell 50. In addition to the elimination of poor anode to shell contact during the formation of the cells, the domed shape of the upper shell is inherently stronger than the flat shape heretofore utilized and inherently resists downward deformation to a much greater degree. Because of this, it is almost impossible to unintentionally harm the electrical contact between the enclosed anode and the upper shell in normal handling of the cell. Also, the domed shape of the anode provides greater physical strength in the anode itself as the zinc is consumedY during cell drainage.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claim rather than by the foregoing description Yand all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by the United States Letters Patent is:

A method of manufacturing a primary Vcell formed from a lower cup-like shell having an upstanding, peripheral wall beaded at the edge thereof and an upper cup-like shell having a depending peripheral Wall and being domed outwardly at the top with a domed top contacting a domed anode received therein, comprising the steps of engaging the lowerredge` of said depending peripheral wall about its periphery with an annular curling die while simultaneously supporting the domed portion of said upper shell in a concave upper idie and moving said dies toward each other to curl said depending peripheral wall about said bead on said upstanding peripheral wall and to cause metal ow in said upper shell to force said domed portion thereof into engagement with the concave portion of said upper die.

References Cited in the le of this patent UNITED STATES PATENTS 1,996,982 Sprague et al. Apr. 9, 1935 2,174,437 Collins Sept. 26, 1939 2,262,836 Deibel Nov. 18, 1941 2,580,664 Drummond Jan. 1, 1952 2,617,863 Stinson Nov. 11, 1952 2,636,063 Schroeder Apr. 2l, 1953 2,812,377 Franquemont Nov. 5, 1957 2,837,593 Rueger June 3, 1958 

